19. Activated sludge Is formed by.
Diffused air aerators.
Adding activated bacteria to digested sludge.
20. The stable products formed by biochemical wastewater treatment processes
are removed by ________________ ___________________, an essential part of
21. Approximately ____________ percent of the sludge from primary sedimentation
units is putrescible organic solids.
22. Under optimum conditions, well-digested sludge is produced in approximated
23. What products are formed In a sludge digester?